sysctl: Refactor the binary sysctl handling to remove duplicate code

Read in the binary sysctl path once, instead of reread it
from user space each time the code needs to access a path
element.

The deprecated sysctl warning is moved to do_sysctl so
that the compat_sysctl entries syscalls will also warn.

The return of -ENOSYS when !CONFIG_SYSCTL_SYSCALL is moved
to binary_sysctl.  Always leaving a do_sysctl available
that handles !CONFIG_SYSCTL_SYSCALL and printing the
deprecated sysctl warning allows for a single defitition
of the sysctl syscall.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>

1 files changed, 58 insertions, 65 deletions

diff --git a/kernel/sysctl_binary.c b/kernel/sysctl_binary.c
index eceeed20ca88..930a31cd708b 100644
--- a/kernel/sysctl_binary.c
+++ b/kernel/sysctl_binary.c
@@ -14,8 +14,6 @@
 #include <linux/ctype.h>
 #include <linux/smp_lock.h>
 
-static int deprecated_sysctl_warning(struct __sysctl_args *args);
-
 #ifdef CONFIG_SYSCTL_SYSCALL
 
 /* Perform the actual read/write of a sysctl table entry. */
@@ -51,7 +49,7 @@ static int do_sysctl_strategy(struct ctl_table_root *root,
         return 0;
 }
 
-static int parse_table(int __user *name, int nlen,
+static int parse_table(const int *name, int nlen,
                        void __user *oldval, size_t __user *oldlenp,
                        void __user *newval, size_t newlen,
                        struct ctl_table_root *root,
@@ -61,8 +59,7 @@ static int parse_table(int __user *name, int nlen,
 repeat:
         if (!nlen)
                 return -ENOTDIR;
-        if (get_user(n, name))
-                return -EFAULT;
+        n = *name;
         for ( ; table->ctl_name || table->procname; table++) {
                 if (!table->ctl_name)
                         continue;
@@ -85,19 +82,13 @@ repeat:
         return -ENOTDIR;
 }
 
-int do_sysctl(int __user *name, int nlen, void __user *oldval, size_t __user *oldlenp,
-               void __user *newval, size_t newlen)
+static ssize_t binary_sysctl(const int *name, int nlen,
+        void __user *oldval, size_t __user *oldlenp,
+        void __user *newval, size_t newlen)
+
 {
         struct ctl_table_header *head;
-        int error = -ENOTDIR;
-
-        if (nlen <= 0 || nlen >= CTL_MAXNAME)
-                return -ENOTDIR;
-        if (oldval) {
-                int old_len;
-                if (!oldlenp || get_user(old_len, oldlenp))
-                        return -EFAULT;
-        }
+        ssize_t error = -ENOTDIR;
 
         for (head = sysctl_head_next(NULL); head;
                         head = sysctl_head_next(head)) {
@@ -112,74 +103,76 @@ int do_sysctl(int __user *name, int nlen, void __user *oldval, size_t __user *ol
         return error;
 }
 
-SYSCALL_DEFINE1(sysctl, struct __sysctl_args __user *, args)
-{
-        struct __sysctl_args tmp;
-        int error;
-
-        if (copy_from_user(&tmp, args, sizeof(tmp)))
-                return -EFAULT;
-
-        error = deprecated_sysctl_warning(&tmp);
-        if (error)
-                goto out;
-
-        lock_kernel();
-        error = do_sysctl(tmp.name, tmp.nlen, tmp.oldval, tmp.oldlenp,
-                          tmp.newval, tmp.newlen);
-        unlock_kernel();
-out:
-        return error;
-}
-
 #else /* CONFIG_SYSCTL_SYSCALL */
 
-SYSCALL_DEFINE1(sysctl, struct __sysctl_args __user *, args)
+static ssize_t binary_sysctl(const int *ctl_name, int nlen,
+        void __user *oldval, size_t __user *oldlenp,
+        void __user *newval, size_t newlen)
 {
-        struct __sysctl_args tmp;
-        int error;
-
-        if (copy_from_user(&tmp, args, sizeof(tmp)))
-                return -EFAULT;
-
-        error = deprecated_sysctl_warning(&tmp);
-
-        /* If no error reading the parameters then just -ENOSYS ... */
-        if (!error)
-                error = -ENOSYS;
-
-        return error;
+        return -ENOSYS;
 }
 
 #endif /* CONFIG_SYSCTL_SYSCALL */
 
-static int deprecated_sysctl_warning(struct __sysctl_args *args)
+static void deprecated_sysctl_warning(const int *name, int nlen)
 {
         static int msg_count;
-        int name[CTL_MAXNAME];
         int i;
 
-        /* Check args->nlen. */
-        if (args->nlen < 0 || args->nlen > CTL_MAXNAME)
-                return -ENOTDIR;
-
-        /* Read in the sysctl name for better debug message logging */
-        for (i = 0; i < args->nlen; i++)
-                if (get_user(name[i], args->name + i))
-                        return -EFAULT;
-
         /* Ignore accesses to kernel.version */
-        if ((args->nlen == 2) && (name[0] == CTL_KERN) && (name[1] == KERN_VERSION))
-                return 0;
+        if ((nlen == 2) && (name[0] == CTL_KERN) && (name[1] == KERN_VERSION))
+                return;
 
         if (msg_count < 5) {
                 msg_count++;
                 printk(KERN_INFO
                         "warning: process `%s' used the deprecated sysctl "
                         "system call with ", current->comm);
-                for (i = 0; i < args->nlen; i++)
+                for (i = 0; i < nlen; i++)
                         printk("%d.", name[i]);
                 printk("\n");
         }
-        return 0;
+        return;
+}
+
+int do_sysctl(int __user *args_name, int nlen,
+        void __user *oldval, size_t __user *oldlenp,
+        void __user *newval, size_t newlen)
+{
+        int name[CTL_MAXNAME];
+        size_t oldlen = 0;
+        int i;
+
+        if (nlen <= 0 || nlen >= CTL_MAXNAME)
+                return -ENOTDIR;
+        if (oldval && !oldlenp)
+                return -EFAULT;
+        if (oldlenp && get_user(oldlen, oldlenp))
+                return -EFAULT;
+
+        /* Read in the sysctl name for simplicity */
+        for (i = 0; i < nlen; i++)
+                if (get_user(name[i], args_name + i))
+                        return -EFAULT;
+
+        deprecated_sysctl_warning(name, nlen);
+
+        return binary_sysctl(name, nlen, oldval, oldlenp, newval, newlen);
+}
+
+
+SYSCALL_DEFINE1(sysctl, struct __sysctl_args __user *, args)
+{
+        struct __sysctl_args tmp;
+        int error;
+
+        if (copy_from_user(&tmp, args, sizeof(tmp)))
+                return -EFAULT;
+
+        lock_kernel();
+        error = do_sysctl(tmp.name, tmp.nlen, tmp.oldval, tmp.oldlenp,
+                          tmp.newval, tmp.newlen);
+        unlock_kernel();
+
+        return error;
 }